FIG. 1 shows such a disk brake in a partially sectioned view. It is possible to recognize a brake caliper 1 comprising a brake disk, which brake caliper is held in an axially displaceable manner on a stationary carrier 2 by two holding devices, whereby the holding devices each comprise a guide bolt 3 fastened indirectly or directly on the carrier 2 and extending away from the brake disk, which bolt contacts the brake caliper 1 indirectly or directly in an opening in the manner of a sleeve bearing. An encasing seal 4 in the form of a bellows is provided in the area between the brake caliper 1 and the carrier 2.
FIG. 2 shows a traditional solution for attaching the seal 4. According to it, the seal is held on the one hand on the guide bolt 3 and on the other hand on the brake caliper, preferably in its guide opening. The holding areas surround in an annular manner. In particular, the free holding on the outer circumference of the guide bolt must be tight in order to ensure the sliding function of the brake caliper on the guide bolt. To this end an annular cord is provided that is elastic and pretensions the seal exclusively in the radial direction. An inwardly facing sealing bead lies in a recess of the guide bolt, which recess is designed as an annular groove. This realizes the positioning. The guide bolt 3 is supported non-positively and positively in a flange area of the carrier 2 and fastened by a cylindrical screw 5, cf. FIG. 1.
In order that the required pretensioning in the radial direction and the positioning are secured for the seal holding, a loose ring is placed above the support area in a recess of the holding sleeve serving as seal in accordance with the traditional solution according to FIG. 2. The ring is a separate additional part.
DE-OS 10 2008 018 468 shows another traditional solution with a separate additional part in the form of a set-on holder. The holder acts radially inward.
The above solutions have the disadvantage that an additional structural part is required to fix the annularly circumferential sealing area. In addition to the expenses for the additional part and the increased assembly expense and the danger that the sealing area can be damaged during the attaching of the separate additional part, the seal can also come loose, e.g., if the additional part separates from the elastomeric seat when used in the field and therefore the required clamping pretension in the radial direction is lost. As a consequence, leaks then occur that adversely affect the sliding function of the brake caliper opposite the guide bolt.
Another disadvantage can be seen in that the contact area between the guide bolt and the flange area of the carrier is unprotected for the non-positive and the positive fit and tends to be susceptible to corrosion.
The invention has the task of further developing the disk brake of the initially cited type in such a manner that the sealing is improved economically as well as functionally. Furthermore, the seal itself should also be improved in this regard.
According to the invention the task posed for a disk brake of the initially cited type is solved in that the pretensioning device reacts to the placing of the holding device.
In other words, an “automatic action” is provided in accordance with the invention in that the placing of the holding device is sufficient to pretension the seal in the recess. Therefore, a separate assembly step for producing the pretension is eliminated, which has economic and functional advantages.
According to the invention the holding device is preferably attached to the carrier, whereby the pretensioning device is constructed on the carrier. Thus, this expressly includes an embodiment in which the pretensioning device is constructed in one piece with the carrier.
According to the invention the holding device can be designed in principle as desired. It is preferably a guide bolt. Furthermore, the guide bolt functioning as holding device is preferably held by a cylindrical screw on the carrier, whereby this preferably takes place in a non-positive and positive connection via a flange area serving as pilot. This has the advantage that e tightening no screwing of the guide bolt with a disadvantageous distortion of the sealing area takes place. Another advantage results from the direct forming of the pretensioning device on the carrier with a contacting of the seal, as a result of which even the support area of the guide bolt is protected against environmental influences.
It is again true for the pretensioning device that it can be designed in principle as desired. However, it is preferably provided in accordance with the invention that it pretensions the seal in the direction of the depth of the recess as well as in the direction transverse to the direction of depth. As a result, the effective sealing surface becomes especially great.
Furthermore, the recess (preferably has in accordance with the invention a rectangular or a U-shaped contour. In this instance the pretensioning in the direction of depth brings about a pressing of the seal on the bottom of the rectangle or of the “U”, in contrast to which the pretensioning in the direction transverse to the direction of depth brings about a pressing of the seal on the lateral limit of the rectangle or of the “U”.
According to the invention it is furthermore preferred that the recess runs around the holding device in an annular manner. In this manner an especially reliable seal of this area can be achieved in that the sliding displacement of the caliper takes place relative to the carrier.
An especially preferred embodiment of the invention provides that the pretensioning device has a control surface that presses against the seal. This design can be realized in an especially simple manner.
The control surface is furthermore preferably annular and has a conical or trumpet-like contour. In particular, a reliable generation of pretensioning forces in the direction of the depth of the recess as well as in the direction transverse to the direction of depth can be achieved with this design.
In order to further increase the seating effect the invention can provide that the seal rests with at least one sealing lip and/or a bead on the bottom of the recess.
Furthermore, the seal preferably has a bead on its side facing away from the bottom of the recess, Such a bead proved to be especially advantageous as regards the striven-for sealing effect.
Furthermore, according to the invention the seal is preferably shaped like a hose. In particular, it is constructed like a bellows in order to also ensure the necessary longitudinal changeability in view of the displaceability of the caliper. The bellows preferably consists of an elastomeric material.
Furthermore, according to the invention the seal preferably has a bead for fastening on the caliper, which bead projects into a recess on the caliper. This design is again especially favourable because it requires no additional structural parts.
Furthermore, the bead projecting into the recess on the caliper preferably rests with at least one sealing tip on the bottom of the recess and/or with at least one sealing lip on a side wall of the recess. This construction serves again to ensure the striven-for sealing effect.
In addition to the disk brake described in detail above the invention also creates a seal for such a disk brake. This seal is constructed according to the above explanations.
The invention is explained in detail in the following with further details using a preferred exemplary embodiment with reference made to the attached drawings.